1. Field of the Invention
This invention relates to electrical communications and more particularly to a system which is automatically responsive to conditions of a liquid level incorporating an electrode.
2. Description of the Prior Art
The prior art has known many types of devices and apparati for determining the liquid level in a reservoir. An important aspect of these devices is the detection of the liquid level within a cooling radiator of a vehicle such as an automobile, truck or the like. Many automobiles and trucks have warning lamps or meters to indicate an excessive temperature of the cylinder head of the vehicle internal combustion engine. However, these temperature sensors are not entirely satisfactory, since in many cases they produce false readings for the operator of the vehicle. These temperature sensors only determine the temperature at a single point in the engine whereas another portion of the engine may be overheating. Damage may occur within the engine before indication by the temperature warning device.
Accordingly, the prior art has produced a variety of liquid level sensing devices for determining the liquid level in the cooling radiator of a vehicle. Many of these devices incorporated an electrical probe connected to an indicator for indicating contact of the liquid to the probe. These devices did not work satisfactorily since the amount of electrical current passing through the cooling liquid into the probe was insufficient to power many indicators such as an incandescent lamp. To overcome this problem, the prior art has complicated the system by incorporating a variety of amplifying devices connected between the probe and the indicator for amplifying the small current flowing within the cooling liquid. These circuits must be temperature compensated and are subject to failure due to extreme operating temperatures, vibrations and the like.
Another serious problem encountered with these apparati is the change in operating level within the cooling radiator when the liquid is in a cool condition or when the liquid is in a hot condition. The apparatus must be able to account for a change in temperature of the cooling liquid to determine whether an adequate amount of liquid exists for both a cool and a hot cooling liquid.
A further disadvantage of these prior art devices is that many of them require a special access hole into the internal portions of the cooling radiator to sense the liquid level therein. Many "do it yourself" consumers are reluctant to make access holes in a vehicle radiator and accordingly, these prior art devices were either installed during fabrication of the radiator or by professional personnel.
Therefore, it is an object of this invention to provide an apparatus which overcomes the aforementioned inadequacies of the prior art devices and provides an improvement which is a significant contribution to the advancement of the pertinent art.
Another object of this invention is to provide an apparatus for cooperation with an existing opening within a cooling radiator of a vehicle to determine the liquid level within the radiator.
Another object of this invention is to provide an apparatus for determining the liquid level in the radiator including sensor means extending into the liquid in the radiator when a sufficient quantity of liquid is contained therein with the sensor having a plurality of curved surfaces for increasing the surface area of the sensor means to provide a sufficient amount of current to power a conventional indicating device.
Another object of this invention is to provide an apparatus for determining the liquid level in a vehicle radiator having a first and a second sensor element mounted at a first and second vertical height within the vehicle radiator with a first and second indicator connected in series with the first and second sensor elements, respectively, and switch means interconnecting the first and second sensor means with the first and second indicators for sensing a cool liquid level and a hot liquid level within the cooling radiator.
Another object of this invention is to provide an apparatus for determining the liquid level in a vehicle radiator comprising a substantially planar conductive element and a plurality of semi-cylindrical elements affixed to the planar member for increasing the surface area of the sensor element at a given vertical height within the vehicle radiator.
Another object of this invention is to provide an apparatus for determining the liquid level in a vehicle radiator comprising insulator means affixed to the underside of a vehicle radiator filling cap and sensor means comprising a substantially spring-shaped element extending downwardly into the vehicle radiator for determining the liquid level therein.
Another object of this invention is to provide an apparatus for determining the liquid level in a vehicle radiator comprising a device for replacing a glass sight window in the side of an existing radiator.
Other objects and a fuller understanding of this invention may be had by referring to the summary of the invention, the description and the claims, taken in conjunction with the accompanying drawings.